Air-cooled internal combustion engine with speed control

ABSTRACT

Air blown over the cooling fins on a cylinder of an internal combustion engine by an engine-driven blower moves a springloaded vane away from a position of abutment against the fins. The vane is linked to a throttle valve in the intake pipe for the fuel mixture and is located on the same side of a reference plane through the cylinder axis which is perpendicular to the axis of the intake pipe, thereby making the connecting linkage short and simple, or even permitting the vane to be mounted on the pivot shaft of the throttle valve. The virtual absence of friction losses in the linkage permits the engine speed to be held closely constant by the vane throttling the fuel supply when the engine speed, and therefore the blower output increases.

United States Patent 1191 Pfister AIR-COOLED INTERNAL COMBUSTION ENGINE WITH SPEED CONTROL [75] Inventor: Bruno Pfister, Sennfeld, Germany [73] Assignee: F ichtel & Sachs AG, Schweinfurt,

Germany [22] Filed: July 7, 1972 [21] Appl. No.: 269,763

[30] Foreign Application Priority Data July 9, 1971 Germany P 21 34 187.7

[52] US. Cl 123/103 B [51] Int. Cl. F02d 11/08 [58] Field of Search 123/103 B, 103 R [56] References Cited UNITED STATES PATENTS 1,660,079 2/1928 Mack 123/103 B 2,525,602 10/1950 Jackson 123/103 B 2,548,334 4/1951 Armstrong 123/103 B 2,836,159 5/1958 Morden 123/103 B 2,935,977 5/1960 Eberline.... 123/103 B Jan. 29, 1974 3,104,657 9/1963 Rice [23/103 B 3,161,186 12/1964 Reichenbach et a1 123/103 B 3,326,196 6/1967 Kaufman 123/103 B 3,650,252 3/1972 Glover et a1. 123/103 B Primary Examiner-Wendell E. Burns Attorney, Agent, or Firm-Kurt Kelman et a1.

[5 7] ABSTRACT Air blown over the cooling fins on a cylinder of an internal combustion engine by an engine-driven blower moves a spring-loaded vane away from a position of abutment against the fins. The vane is linked to a throttle valve in the intake pipe for the fuel mixture and is located on the same side of a reference plane through the cylinder axis which is perpendicular to the axis of the intake pipe, thereby making the connecting linkage short and simple, or even permitting the vane to be mounted on the pivot shaft of the throttle valve. The virtual absence of friction losses in the linkage permits the engine speed to be held closely constant by the vane throttling the fuel supply when the engine speed, and therefore the blower output increases.

12 Claims, 6 Drawing Figures PATENTED JAN 2 9 I974 SHEET 1 [1F 3 PATENTEB JAN 2 91974 SHEET 2 BF 3 AIR-COOLED INTERNAL COMBUSTION ENGINE WITH SPEED CONTROL This invention relates to air-cooled internal combustion engines, and particularly to an improvement in such an engine in which a stream of cooling air is provided by an engine-driven blower, and a vane exposed to the air stream is linked to a throttle in the fuel supply conduit to reduce the fuel supply when the engine speed, and thus the speed of the air stream, exceeds a set value.

The known devices permit only a very rough adjustment of engine speed, and are practically limited to the prevention of overspeeding of the engine. The lack of sensitivity of the known devices has been found to be due to the fact that the vane is arranged in the blower or close to the blower and remote from the fuel mixture supply. The linkage connecting the vane to the fuel supply throttle is necessarily long and includes several hingedly connected members. The small controlling force provided by the moving vane is largely absorbed by friction in the hinged connections. Turbulence created in the air stream about the vane in the known devices also prevents the force available from the vane from being even approximately proportional to the speed of the engine or of the blower coupled to the engine. The vane is not readily accessible for cleaning and maintenance, and these operations are not conveniently performed on the relatively complex linkage.

The invention aims at avoiding the shortcomings of the known devices and to connect a vane in the cooling air stream generated by an engine-driven blower with a valve in the fuel supply conduit in such a manner that even small changes in engine speed and in the resulting speed of the air stream can be sensed by the vane, and the force exerted on the vane can be transmitted to the valve without significant loss for a more precise engine speed control than was available heretofore.

With these objects in view, the invention movably secures the sensing vane to the cylinder in such a manner that the vane is moved away from a position contiguously adjacent selected cooling fins on the cylinder in response to an increase in the rate at which an air stream is blown over the fins by a blower coupled to the output shaft of the engine. The vane and the fuel supply conduit of the engine are located on the same side of a reference plane including the cylinder axis, the plane being perpendicular to the axis of the terminal portion of the conduit which directly communicates with the cylinder. The vane is resiliently biased toward the afore-mentioned position thereof adjacent the selected cooling fins.

Other features, additional objects, and many of the attendant advantages of this invention will readily become apparent as the invention becomes better understood by reference to the following detailed description of preferred embodiments when considered in connection with the appended drawing in which:

FIG. 1 shows an internal combustion engine of the invention in side elevation;

FIG. 2 illustrates the engine of FIG. 1 in rear elevation;

FIGS. 3 and 4 show a modification of the engine of FIGS. 1 and 2 in respective corresponding views;

FIG. 5 illustrates a portion of the device of FIG. 3 in enlarged section on the line V V; and

FIG. 6 shows yet another engine of the invention in a fragmentary view corresponding to that of FIG. 5.

Referring now to the drawing in detail, and initially to FIGS. 1 and 2, there is seen as much of an air-cooled, single-cylinder gasoline engine as is needed for an understanding of this invention. Its crank-case assembly 10 includes a reducing gear transmission of which only the casing 12 and the output shaft 14, coaxial with the non-illustrated crankshaft, are seen. The cylinder 16 fixedly mounted on the crank-case assembly 10 is provided with integrally cast cooling fins 18 which, except for those provided on the cylinder head, are fiat, annular discs extending in respective planes perpendicular to the cylinder axis.

The cylinder head centrally carries a spark plug 20. An intake pipe 22 leads radially to an intake port of the cylinder, the port being obscured by the pipe 22 and radially spaced from a reference plane BB through the cylinder axis and perpendicular to the axis of the pipe 22. The intake pipe 22 is the terminal portion of a supply conduit which supplies a combustible fuel mixture to the cylinder 16, and which also includes a car buretor 24 equipped with an air filter 26.

The non-illustrated crankshaft of the engine extends into a blower casing 28, and thus couples the impeller or rotor 30 of a centrifugal blower to the output shaft 14. The discharge duct 32 of the blower terminates in a sheet metal shroud 34 which envelops the fins 18 with little clearance and. guides the air discharged from the duct 32 into the path between the fins 18 which are approximately parallel to the reference plane 8-8. The shroud 34 is open in the direction of air flow, and the fins 18 project in the same direction beyond the shroud. The blower draws air from the ambient atmosphere into a frontal opening of the casing 28, not shown, and aligned with the shaft 14.

A vane 38 conforming to the approximately cylindrical overall contour of the fins 18 on the top portion of the cylinder 16 is attached to an upright pivot shaft 39 joumaled and axially secured in two bearing rings 40, 42 on the rear edge of the shroud 34. A radial arm 44 fixedly fastened to the lower end of the shaft 39 has an elongated opening 46 which receives a crank 48 on the shaft 50 of a throttle valve 52 in the intake pipe 22. When the vane 38 is pivoted away from the ribs 18 by the pressure of air flowing through the channels 54 bounded by the ribs 18 and the shroud 34, the valve 52 is turned by the shaft 50 to reduce the effective flow section of the intake pipe 22. Such pivoting movement of the vane 38 is opposed by a helical spring 53 attached to the vane 38 and to the shroud 34 and biasing the vane toward the illustrated position of abutting engagement against the ribs 18.

Because the output rate of the blower rotor 30 increases with the engine speed, the force exerted by the intercepted air on the vane 38 is directly related to the engine speed, and this speed can be kept approximately constant within the load capacity of the engine by the linkage 44, 48 connecting the vane 38 to the throttle valve 52 with minimal friction losses.

In the modified arrangement shown in FIGS. 3 and 4, parts identical with or analogous to elements described with reference to FIGS. 1 and 2 have been provided with the same reference numerals augmented by 100. The crank-case assembly 110, transmission casing 112, output shaft 114, spark plug 120, intake pipe 122, carburetor 124, air filter 126, blower casing 128 and rotor 130, blower discharge duct 132, and throttle valve 152 are not significantly different from the corresponding elements in FIGS. 1 and 2. The cylinder 116, the fins 118, and the shroud 160 form a unitary casting which bounds the channels 154 through which the blower output is discharged. The intake end of the shroud is fitted into the orifice 164 of the blower discharge duct 132. A reference plane BB through the axis of the cylinder is perpendicular to the radial intake pipe 122 and to a radius drawn through the non-illustrated intake port.

The vane 138 is a flat piece of sheet metal having a vertical edge attached to the shaft 166 of the throttle valve 152 which projects upward from a bearing 168 on the intake pipe 122. As is best seen in FIG. 5, the vane 138 extends from its pivot on the intake pipe 122 through an opening 170 in the shroud 160 into the path of the air discharged from the duct 132. The fins 118 coextensive with the vane 138 in the direction of the cylinder axis have notches 174 to provide an unobstructed space 176 in which the vane 138 may move under the air pressure, the movement being opposed by a helical tension spring 153, as described with reference to spring 53. The two ends of the spring are attached, respectively, to the vane 138 and to a rocker 172 which may be pivoted by a cable 178 connected to a non-illustrated, manually operated control lever for varying the tension of the spring 153, and for thereby setting the speed at which the engine is held by the shaft 166 directly linking the throttle valve 152 to the vane 138.

The portion of the cylinder 116 located on the same side of the reference plane BB as the intake pipe 122 is cooled by the fuel mixture supplied from the carburetor 124, and the notches 174 do not unduly reduce the cooling effect achieved by the air streams in the channels 154, although the fins 118 which are located on the same side of the plane BB are narrower than the corresponding fins on the other side of the reference plane, the fins being otherwise symmetrical relative to the plane.

In the further modified embodiment of the invention shown in FIG. 6, which is identical with that illustrated in FIGS. 3 to 5 as far as not shown otherwise, corresponding elements have been designated by reference numerals further augmented by 100.

The cylinder, its fins 218, and a shroud 260 are integrally cast. The location of the intake pipe 222 defines a reference plane BB through the cylinder axis at right angles to the pipe 222 or to its axis, but the pipe 222 is not radial relative to the cylinder axis. Whereas the pipes 22 and 122 are located in a plane corresponding to the radial plane N in FIG. 6, the intake pipe 222, the carburetor 224, the air filter 226, and the flap 238 mounted on the shaft 266 of the throttle valve, as described above, are jointly located in a quadrant bounded by planes U, V through the cylinder axis which are angularly offset 45 in opposite directions from the plane N so that the plane N bisects the quadrant. The vane 238 enters the shroud 260 through an opening in the latter for pivotal movement in a space 276 provided by notches in the fins 218.

Air pressure holds the vanes 238 in the fully drawn position in which the associated throttle valve reduces the effective flow section of the intake pipe 222 to a minimum. A helical tension spring 253 biases the vane 238 toward the position indicated in broken lines in which the throttle fully opens the pipe 222.

Friction losses in the linkage between the vane and the fuel supply throttle are at a minimum in the devices illustrated in FIGS. 3 to 6, in which the linkage consists of the common pivot shaft of the vane and the throttle, and the pivot shaft simultaneously assumes the function of securing the sensing vane to the engine cylinder. Friction losses caused by engagement of the crank 48 on the throttle shaft 50 with the slotted arm 44 on the pivot shaft 39 of the vane 38 in the apparatus of FIGS. 1 and 2, however, are too small to reduce the sensitivity of the speed control device to a significant extent. The engine speed is kept as uniform as the inherent inertia and hysteresis of the system permits.

The invention has been described with reference to an engine which draws a mixture of liquid and partly vaporized fuel and of air to combustion from a carbure tor. However, the invention is readily adapted to control a fuel injection system or an engine operated by means of a gaseous fuel in which the fuel supply conduit includes neither a carburetor nor an air filter as more specifically illustrated in the drawing.

The numerical relationship between the engine speed and the blower speed is not directly relevant to this invention, and the blower may be connected to the crankshaft of the engine by a transmission which turns the input shaft of the blower at a speed lower or higher than the speed of the crankshaft. The specific coupling drivingly connecting the output shaft of the engine to the blower is thus not critical and may be chosen to suit specific conditions.

It will be understood, therefore, that the foregoing disclosure relates only to preferred embodiments, and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

What is claimed is:

1. In an internal combustion engine including a rotary output shaft,

a cylinder having an axis,

cooling fins on the outer face of said cylinder,

a supply conduit for supplying fuel to said cylinder,

a terminal portion of said conduit communicating with said cylinder and having an axis perpendicular to a reference plane including the axis of said cylinder, whereby said terminal portion is located on one side of said plane,

valve means movable in said conduit for varying the effective flow section of the conduit,

blower means drivingly coupled to said output shaft for blowing a stream of air over said fins at a rate corresponding to the rotary speed of said output shaft,

sensing means for sensing said rate, said sensing means including a vane member exposed to said stream for movement thereby in response to a change in said rate, and

linking means linking said sensing means to said valve means for moving the valve means in response to the movement of said vane member,

the improvement which comprises:

a. securing means securing said vane member to said cylinder for movement away from a predetermined position relative to selected ones of said fins on said one side of said plane in response to an increase in said rate; and

b. yieldably resilient biasing means biasing said vane member toward said position.

2. In an engine as set forth in claim 1, said selected fins bounding a channel directed toward said vane member, and said blower means including means for blowing said stream through said channel toward said vane member.

3. In an engine as set forth in claim 2, said vane member, when in said position thereof, being contiguously adjacent said selected fins.

4. In an engine as set forth in claim 2, said position being located in a quadrant bisected by a plane perpendicular to said reference plane and including said axis.

5. In an engine as set forth in claim 3, said securing means securing said vane member to said cylinder for pivoting movement about an axis substantial parallel to the axis of said cylinder.

6. In an engine as set forth in claim 5, said selected fins on said one side having a smaller surface area than corresponding fins on the other side of said reference plane, the fins other than said selected and said corresponding fins being substantially symmetrical relative to said reference plane.

7. In an engine as set forth in claim 3, said blower means blowing said stream through said channels in a direction substantially parallel to said reference plane.

8. In an engine as set forth in claim 7, a shroud enveloping said fins and bounding said channels in a direction transverse to said reference plane.

9. In an engine as set forth in claim 8, a portion of said vane member being located between said shroud and said selected fins when the vane member is in said position thereof.

10. In an engine as set forth in claim 9, said securing means securing another portion of said vane member outside said shroud to said cylinder, said shroud being formed with an opening for passage of said vane member.

11. In an engine as set forth in claim 3, said securing means fixedly fastening said vane member to said valve and thereby constituting said linking means.

12. In an engine as set forth in claim 3, said vane member when in said position thereof substantially conforming to the contour of said selected tins and abuttingly engaging at least one of said selected fins. 

1. In an internal combustion engine including a rotary output shaft, a cylinder having an axis, cooling fins on the outer face of said cylinder, a supply conduit for supplying fuel to said cylinder, a terminal portion of said conduit communicating with said cylinder and having an axis perpendicular to a reference plane including the axis of said cylinder, whereby said terminal portion is located on one side of said plane, valve means movable in said conduit for varying the effective flow section of the conduit, blower means drivingly coupled to said output shaft for blowing a stream of air over said fins at a rate corresponding to the rotary speed of said output shaft, sensing means for sensing said rate, said sensing means including a vane member exposed to said stream for movement thereby in response to a change in said rate, and linking means linking said sensing means to said valve means for moving the valve means in response to the movement of said vane member, the improvement which comprises: a. securing means securing said vane member to said cylinder for movement away from a predetermined position relative to selected ones of said fins on said one side of said plane in response to an increase in said rate; and b. yieldably resilient biasing means biasing said vane member toward said position.
 2. In an engine as set forth in claim 1, said selected fins bounding a channel directed toward said vane member, and said blower means including means for blowing said stream through said channel toward said vane member.
 3. In an engine as set forth in claim 2, said vane member, when in said position thereof, being contiguously adjacent said selected fins.
 4. In an engine as set forth in claim 2, said position being located in a quadrant bisected by a plane perpendicular to said reference plane and including said axis.
 5. In an engine as set forth in claim 3, said securing means securing said vane member to said cylinder for pivoting movement about an axis substantial parallel to the axis of said cylinder.
 6. In an engine as set forth in claim 5, said selected fins on said one side having a smaller surface area than corresponding finS on the other side of said reference plane, the fins other than said selected and said corresponding fins being substantially symmetrical relative to said reference plane.
 7. In an engine as set forth in claim 3, said blower means blowing said stream through said channels in a direction substantially parallel to said reference plane.
 8. In an engine as set forth in claim 7, a shroud enveloping said fins and bounding said channels in a direction transverse to said reference plane.
 9. In an engine as set forth in claim 8, a portion of said vane member being located between said shroud and said selected fins when the vane member is in said position thereof.
 10. In an engine as set forth in claim 9, said securing means securing another portion of said vane member outside said shroud to said cylinder, said shroud being formed with an opening for passage of said vane member.
 11. In an engine as set forth in claim 3, said securing means fixedly fastening said vane member to said valve and thereby constituting said linking means.
 12. In an engine as set forth in claim 3, said vane member when in said position thereof substantially conforming to the contour of said selected fins and abuttingly engaging at least one of said selected fins. 